Imaging Vertical Earthquake Cycle Crustal Deformation of the San Andreas Fault System Utilizing the GAGE Facility

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Major earthquakes along the San Andreas Fault system in southern California threaten millions of people and billions of dollars in property and infrastructure, which makes understanding the physics of earthquakes key in addressing a critical societal need for improved seismic hazard estimates. This project is using state-of-the-art geodetic data provided by the GAGE (Geodesy Advancing Geosciences and EarthScope) Facility and EarthScope to understand how Earth's crust deforms in response to plate tectonics and other processes. The project is focused particularly on understanding vertical motions, which may be related to groundwater withdrawal and snow loading and the migration, extraction, and injection of crustal fluids in addition to faulting and earthquake processes. Detection of anomalous vertical motions in these data will not only improve the quality of earthquake cycle strain rate estimates, but is also a valuable resource for climate, hydrologic, oceanographic, and earthquake engineering communities.The team is focusing on studying vertical deformation using a synthesis of GAGE Facility (Global Positioning System and InSAR) and coastal tide gauge data spanning the Pacific-North American plate boundary. The project is developing well-constrained time-series model products of 3D earthquake cycle deformation using integrated high accuracy GPS point measurements, high spatial resolution InSAR measurements, and long-period tide gauge vertical time series observations. This research project has four main objectives: (1) preparing a contemporary high-resolution GPS-constrained 4D model of vertical and horizontal crustal deformation of the SAFS; (2) using these models to correct inherent errors in InSAR data from new satellites through integrated analysis of GPS and InSAR; (3) construction of a refined 4D time series of crustal deformation derived GPS, InSAR, and tide gauge time-series data; and (4) detecting and understanding non-tectonic deformation common in both InSAR and GPS data. In addition, the team is developing outreach materials describing how InSAR observations are made and used in modeling crustal deformation and distributing those via the Active Earth kiosks supported by NSF, and is releasing software tools to enable geodetic data analyses by the broad Earth science community.